A cable usable for incorporation in medical apparatus.
It is old to provide a cable by winding one or more strands of wire about a linear central wire in contact with the wire throughout at least a major part of the axial length of the central wire. However with such prior art cables the useful life is shortened due to fracturing of the central wire, particularly when being of relatively small diameters. Further such cables can not be bent about relatively tight radii and still satisfactorily transfer torque from one end to the other with high resolution, in part due to the solid core wire taking a set. Additionally it is hard to clean out all of the foreign material entrapped during the manufacture of the solid lumen helical cables.
Oldbergh U.S. Pat. No. 3,267,697 discloses a universal joint for automobiles that includes a plurality of multifilar spring units in telescoped relationship. The inside diameter of the intermediate spring unit is slightly less than the outside diameter of the inner spring unit. During assembly the inner unit is preloaded to cause radial contraction and after being inserted into the intermediate unit, is allowed to expand. The radial intermediate coil is wound in the opposite direction from that of the winding of the inner and outer coils. Ruegg U.S. Pat. No. Re 25,543 and Hotchkiss U.S. Pat. No. 1,228,439 each disclose a flexible coupling member and a flexible shaft respectively which each includes an intermediate coil wound in a direction opposite that of the radially inner and outer coils. Sperling U.S. Pat. No. 1,279,773 also discloses a flexible shaft having oppositely wound coils.
Lerwick U.S. Pat. No. 3,811,446 discloses endarterectomy apparatus that includes an electric motor 11 which drives a pair of springs that in turn drive the input shaft of a converter. The inner coil is multifilar and is enclosed by an outer helical spring. Wampler U.S. Pat. No. 4,625,712 discloses an intravascular blood pump drivenly connected by a flexible shaft to a support unit that is located outside of the human body.
Kline et al U.S. Pat. No. 3,749,036 discloses a guide wire having an outer spring coil that extends between the proximal and distal tips, and in two embodiments an inner coil only in the distal end portion of the outer coil and in two embodiments a wire core extends between the tips.
Each of Takahashi U.S. Pat. No. 4,178,810 and Sanagi U.S. Pat. No. 4,632,110 discloses a coil spring having forceps mounted on one end thereof and a manipulating handle mounted on the other end. Auth U.S. Pat. No. 4,646,736 discloses transluminal thrombectomy apparatus having a shaft comprised of a 3 mil gold wire helically wound about a 4 mil stainless steel arbor for rotating a tip and being driven by a prime mover. Mac Lean U.S. Pat. No. 2,955,592 discloses a medical instrument having a sheath that includes an outer coil and an inner coil. Willson discloses a vascular tissue removing device that includes a single layer multistrand closely spaced helically wound coil of wire (U.S. Pat. No. 3,749,085).
Kensey et al U.S. Pat. No. 4,664,112 discloses a catheter bendable about a radius of curvature, e.g. 3xe2x80x3, and having a working head rotated at a high speed by a drive assembly. In one embodiment the drive assembly includes two interlaced helical wires having their distal ends joined to a cutting tip. The two wires are wound about a guide wire to rotate about a guide wire, are of outside diameters of 0.01xe2x80x3, and are loosely wound.
Kline U.S. Pat. No. 3,757,768 discloses a sprint guide catheter wherein a plastic tube is heat shrunk over a coil spring while O""Neil U.S. Pat. No. 4,145,247 discloses a pacer lead wherein a coil conductor is enclosed in an insulating layer.
Each of Samson et al U.S. Pat. No. 4,538,622 and Leary U.S. Pat. No. 4,545,390 discloses a PCTA guide wire that includes a main wire having a proximal cylindrical portion, a tapered intermediate portion and a cylindrical distal end portion of a smaller diameter than the proximal cylindrical portion and a helically wound coil having a proximal portion joined to the tapered portion, and a distal tip joined to one or both of the main wire distal end and the coil. In Samson the coil includes two coil portions of different materials.
U.S. Pat. No. 4,516,972 to Samson discloses a guiding catheter that includes an inner liner, a first plurality of ribbons helically wound on the inner liner, a second plurality of ribbons helically wound in the opposite direction on the first ribbons and an outer plastic jacket. The helices of the ribbons are different pitches in different regions along the length of the inner member.
One of the problems encountered in the prior art is the lack of a very small diameter, highly flexible cable that has a relatively long life even when bent about relatively small radii for forming a part of medical apparatus, for example rotating or otherwise moving all or part of a medical device or medical subassembly and is medically clean. In order to overcome problems such as the above as well as others this invention has been made.
Hollow lumen cables that are usable for driving medical devices, or mounting medical devices that include a multifilar inner coil that in a non-assembled relaxed condition is of a given outer coil disameter that is larger than that of the outer coil inner diameter wherein in an assembled condition the inner and outer coils are oppositely wound with the outer coil inner peripheral surface being in an interference fit relationship with the outer peripheral surface of the inner coil. The cable may be used for forming a drive connection between a powered prime mover and a pump mountable in a human body, or driving an atraumatic tip or have a manually manipulated handle mounted on one axial end and, for example a forceps mounted on the opposite end, or form a part of a guide wire. Advantageously the outer coil may be of an outer coil diameter of about {fraction (1/16)}xe2x80x3 or less. The cable also may be used in forming a catheter.
One of the objects of the invention is to provide a new and novel hollow lumen cable for use in the medical field. In furtherance of the above object it is another object of this invention to provide a new and novel method of making such a cable. Another object of this invention is to provide a new and novel cable usable in the medical field that is of a relatively small outer diameter, and can form a drive connection that is rotatable at relatively high speeds with high torque resolution even when bent about relatively tight radii of curvature including through a circle and is medically clean. Still another object of this invention is to provide new and novel guide wire means that incorporates the cable of this invention.
A different object of this invention is to provide a new and novel catheter that has very good torque transmitting characteristics. An additional object of this invention is to provide a new and novel guide wire having a main wire and a spring coil, and the method of making such a guide wire.
For purposes of this application a xe2x80x9chollow lumen cablexe2x80x9d relates to a cable wherein none of the strands of helically wound wires are wound around and in contact with a linear central wire (mandrel). Further for the purposes of this application xe2x80x9cpress fitxe2x80x9d refers to the relationship between a coil and a guide wire main wire wherein the coil in its relaxed condition has a smaller inner diameter than the outer diameter of at least a major part of the axial length of the portion of the main wire that is thereafter extended into the coil, and the coil is partially unwound to have an inner diameter that is larger than the outer diameter of the main wire that is to be extended thereinto, and be engaged thereby and after the main wire is extended into the coil, the force retaining the coil in its partially unwound condition is released to allow the coil to resiliently return toward its fully relaxed condition to form a clamping fit with the radially adjacent part of the main wire that is to be engaged thereby which is of a larger diameter than the inner diameter of the coil prior to the partial unwinding of the coil.
In the event that a coil spring is formed by winding a coil wire around an axial cylinder portion of a guide wire main wire, upon the release of the winding force the wound coil expands, even if tightly wound around the main wire. Accordingly when turning the main wire, whipping of the distal end takes place, provided the main wire is not of an undesireable degree of stiffness, or a relatively large diameter. Such whipping takes place even if the proximal end and at least part of the distal end portion of the coil is brazed, soldered or similarly fixedly secured to the main wire. Even if the coil were brazed to the main wire before releasing the unwinding pressure the coil would be in intimate fitting relationship to the cylindrical portion of the main wire that the coil was in abutting relationship with and as a result there would be an undesirable amount of stress in the coil. Additionally such whipping occurs if the coil is formed to have an inner diameter only slightly larger than the maximum diameter of the cylinder portion of a guide wire main wire that is to be extended into the coil, and after the formation of the coil and sliding the main wire to extend into the coil, the coil proximal end and distal end portions are brazed or similarly fixedly secured to the main wire. The term xe2x80x9cpress fitxe2x80x9d as used in this application does not include the methods referred to in this paragraph.